1. Field of the Invention
This invention relates generally to a snorkel such as used by spear fishermen. More particularly, this invention relates to a mechanism for more efficient purging of the water column and more efficient water drainage to enhance snorkel breathing.
2. Prior Art
The experienced free diver, using a snorkel, maintains his face down underwater even as he returns to the surface following a short dive. Such excursions or other maneuvers fill his snorkel tube with water that must be purged in order to resume snorkel breathing. Water is normally purged by producing a short, abrupt blast of air. The water moves essentially as a near solid mass before the water has a chance to break apart and slip into the airstream. The solid mass of water, propelled by an exhalation by the user will purge the greater amount of water from the breathing tube and will require the least amount of effort. The exhalation effort required is considerable, but easily produced by a strong diver. However, not all persons who use snorkels are capable of generating the required exhalation effort. One solution to the aforementioned problem is that of providing purge valves which allow the column of water in the snorkel tube to drop to the level of the surrounding water which would otherwise be trapped. One particularly advantageous snorkel configuration which utilizes a large purge valve at the end of a branch or bypass conduit connected to the snorkel tube at a place spaced from the snorkel mouthpiece, is disclosed in U.S. Pat. No. 4,278,080 issued July 14, 1981 to the assignee of the present invention. While the snorkel disclosed in the aforementioned patent is a significant improvement over the prior art, additional improvements are desirable in order to further decrease the effort required to purge the snorkel of water and also in order to more effectively rid the snorkel and particularly the mouthpiece portion thereof of any remaining water which might otherwise interfere with the breathing effort.
In addition to the aforementioned U.S. Patent, the following patents are also relevant to the general art of snorkels:
U.S. Pat. No. 46,902 Hawkins PA1 U.S. Pat. No. 3,467,091 Aragona PA1 U.S. Pat. No. 3,653,086 Gongwer PA1 U.S. Pat. No. 3,768,504 Rentsch, Jr. PA1 U.S. Pat. No. 3,860,042 Green PA1 U.S. Pat. No. 3,993,060 Mitchell PA1 U.S. Pat. No. 4,066,077 Shamlian PA1 U.S. Pat. No. 4,071,024 Blanc PA1 U.S. Pat. No. 4,230,106 Geeshin, et al PA1 U.S. Pat. No. 4,380,232 Doyle PA1 U.S. Pat. No. 4,562,836 Penon PA1 U.S. Pat. No. 4,583,536 Jan PA1 U.S. Pat. No. 4,610,246 Delphia PA1 U.S. Pat. No. 4,655,212 Delphia PA1 U.S. Pat. No. 4,708,135 Arkema